Specific functioning of networks in the nervous system depends not only upon the wiring diagram for neuronal interconnection, but also upon the proprties of particular synapses. Within the same network, postsynaptic conductances vary in sign and duration, while some synapses combine several responses to show polyphasic conductance changes. This project will identify and characterize types of functional elements available to an actual neural network, the way in which they are combined, and the functional consequences of their use. The goal is both a generalizable biophysical description of synapses and an understanding of the role of the synapses in the behavior of a cell and network. Specific questions to be asked include: What kinetic properties of receptors determine synaptic current duration? Is synaptic potential amplitude more plastic than its duration? What are the relative contributions of multiple-component synaptic potentials and direct/indirect synaptic information transfer? The preparation used, the buccal ganglia of the mollusc Aplysia californica contains a ppopulation of synaptically interconnected neurons well suited to these studies. Techniques employed include intracellular recording from pre- and postsynaptic neurons, voltage-clamping of postsynaptic potentials, and patch clamping single synaptic channels. The correlations between single-channel kinetics and synaptic efficacy, function of multi-component synapses, and principles of organization of identified cell networks drawn from this preparation may prove applicable to experimentally less accessible populations of vertebrate neurons.